1. Field of the Invention
The present invention relates to an ink jet print head for use in printers, facsimile machines, plotters, word processors, etc., and an ink jet printer using the ink jet print head, and more particularly, to an improved structure of pressure chambers and piezoelectric elements for discharging ink from nozzles in a kayser type ink jet print head.
2. Description of the Related Arts
An ink jet printer using an ink jet print head is conventionally known. The ink jet printer is of a type where the print head ejects fine particles of ink without bringing the print head into contact with the print medium. This will lead to advantages such as a wide technical possibility independent from the print medium and the ablity of high-speed printing.
FIGS. 8(a) and 8(b) depict a structure of a kayser type ink jet print head according to a conventional example (See Japanese Patent Laid-open Pub. No. 5-254140). As shown in FIG. 8(a), an ink jet print head comprises a circularly extending ink supply path 42, and a plurality of pressure chambers 44 circularly arranged inside the ink supply path 42 for receiving ink from the ink supply path 42 and reserving the ink. The pressure chambers 44 communicate with corresponding ink paths 46 which lead the ink derived from the pressure chambers 44 to nozzles 48 depicted in FIG. 9. Also, as shown in FIG. 8(b), this embodiment has a plurality of circularly arranged piezoelectric elements 50. The piezoelectric elements 50 are correspondingly adhered to the pressure chambers 44 as shown in FIG. 8(a).
Upon performing printing by use of this ink jet print head, a voltage is applied to the piezoelectric elements 50 for selective excitation thereof.. Then, the ink from the ink supply path 42 flows into the pressure chambers 44 corresponding to the thus excited piezoelectric elements 50. The ink further flows from the pressure chambers 44 through the ink paths 46 toward the nozzles 48. The flow rate of the ink corresponds to the volume displacement of the pressure chambers 44. A desired quantity of ink is then discharged from the nozzles 48 in hounds tooth arrangement as shown in FIG. 9, to thereby enable stable multi-dot printing. In order to excite the pressure chambers to accomplish stable printing quality in the conventional ink jet print head, a voltage in the order of 40 V must be applied to the piezoelectric elements 50.
It is, however, desirable to further reduce the voltage applied to the piezoelectric elements in view of the production steps including IC mounting, electronic wave faults, safety, and so on. Nevertheless, as described above, a voltage of about 40 V must be applied to the piezoelectric elements to obtain a stable printing quality in the conventional ink jet print head.
To improve the printing quality, it is preferable to increase the discharge quantity of ink while preventing the apparatus from being enlarged in size.
Also, in view of the production cost of the ink jet print head, reduction in size, and so on, it is preferable to form smaller pressure chambers and smaller piezoelectric elements while maintaining a desired discharge quantity.